Tilting dozer blade

ABSTRACT

A bulldozer construction for a tractor comprises a dozer blade extending across the front of the tractor, a pair of strut assemblies each connected at one end to receive a thrust from the blade and to transmit it to the tractor. Each assembly includes a strut of fixed length and a sub-assembly of variable length and hydraulic actuators operable by the tractor driver without dismounting from the tractor, to vary the effective length of the two sub-assemblies in unison to give a pitching movement to the blade. The actuators are also operable to vary the effective length differentially to give a tilting movement to the blade.

[30] Foreign Application Priority Data Feb. 4, 1969 Italy ..12423 A/69 [52] US. Cl ..172/804, 172/809 [51} Int. Cl. ..E02f 3/76 [58] Field of Search 1 72/80 1-809 [56] References Cited UNITED STATES PATENTS 3,441,092 4/1969 Drone ..172/803 2,224,725 12/1940 Felt, Jr ....172/804 3,477,151 11/1969 Zanella 1 72/802 X 3,529,678 9/1970 Teasdale ..172/809 X United States Patent [151 3,661,215 Pensa- May 9, 1972 [54] TILTING DOZER BLADE 2,766,536 10/1956 Perkins ..172/807 X 3,061,955 11/1962 Violette ..172/802 [72] Invent Italy 3,503,457 3/1970 Smith et a1 172/803 [73] Assignee: Massey-Ferguson Services N.V., Curacao, 3,049,820 8/1962 Lichti ..172/803 Netherlands Antilles 3,513,916 5/ 1970 Hyler ..172/809 X [22] Filed: Jan. 29, 1970 Primary Examiner-Robert E. Pulfrey Assistant Examiner-R. T. Rader Attorney-Gerhardt, Greenlee & Farris ABSTRACT A bulldozer construction for a tractor comprises a dozer blade extending across the front of the tractor, a pair of strut assemblies each connected at one end to receive a thrust from the blade and to transmit it to the tractor. Each assembly includes a strut of fixed length and a sub-assembly of variable length and hydraulic actuators operable by the tractor driver without dismounting from the tractor, to vary the effective length of the two sub-assemblies in unison to give a pitching movement to the blade. The actuators are also operable to vary the effective length difierentially to give a tilting movement to the blade.

5 Claims, 4 Drawing Figures Invenlor Mfr/w Pf/VSA BYQgMgM W Attorneys TILTING DOZER BLADE The present invention relates to a bulldozer blade construction for use with industrial or agricultural tractors and especially with crawler tractors.

The construction is concerned particularly with means for pitching the dozer blade and tilting it. Pitching movements occur when the top and bottom of the blade move forward or backward relatively to each other. Tilting movement occurs when the ends of the blade move up or down relatively to each other.

It is known to use screws or extensible members to effect tilt and pitch of the dozer blade. These mechanisms either have to be adjusted by hand or are exposed to dirty conditions and must be comparatively strong.

It is an object of the present invention to overcome these difficulties and particularly to permit remote control of these movements of the blade from the driver's position. Also in particular, the invention enables the actuating mechanisms to be removed from a dirty zone and to be made of comparatively small size.

According to the present invention a bulldozer construction for a tractor is comprising a dozer blade extending across the front of the tractor, a pair of strut assemblies each connected at one end to receive a thrust from said blade and to transmit it to said tractor, each said assembly consisting of a strut of fixed length and a sub-assembly of variable length and actuating means operable by the tractor driver without dismounting from the tractor, to vary the effective length of the two sub-assemblies in unison to give a pitching movement to the blade. The means are also operable to vary the effective length differentially to give a tilting movement of the blade.

The sub-assembly consists of a first link pivotally connected at one end to the strut and a second link pivotally connected at one end of the first link and at the other end through a transversely movable pivot to the blade, and guide means to maintain substantially the positional relationship between the first link and the strut.

The control means to vary the effective lengths of the subassemblies consists in part of a pair of double acting piston and cylinder rams containing four fluid chambers two of which are permanently connected together to form a common chamber the ram pistons or cylinders being connected to move the movable pivots. The piston rods are preferably connected to the movable pivots and a control located near to the driver is provided to direct pressure fluid to the common chamber to cause the pistons to move the movable pivots so that both subassemblies are extended or contracted by an equal amount to give a pitching movement. As a further preference the control is able to close the common chamber and direct pressure fluid to one of the other chambers to cause both pistons to move their respective movable pivots so that one sub-assembly is extended while the other is contracted or vice versa.

In the case where the bulldozer blade is required to be placed at an angle to the direction of vehicle motion the blade is provided with a center pivot on a U-shaped frame and the strut assemblies are repositioned, one forward and one back, and are recoupled to the U-frame at the positions desired. To prevent this adjustment from interfering with the pitch and tilt movement corresponding alternative pivotal connection points are provided between the first and second links.

The preferred embodiments of the invention will now be described by reference to the accompanying drawings of which:

FIG. 1 is a view of the construction applied to a transversally mounted bulldozer blade and includes certain hydraulic control diagrams;

FIG. 2 is a similar view of the construction applied to a blade which is capable of being placed at an angle to the tractor;

FIG. 3 is a diagrammatic sketch of the actuator means and one form of the hydraulic control; and

FIG. 4 is a diagrammatic sketch of a second and more simplified form of the hydraulic control.

Referring to FIG. 1, it will be seen that the construction on one side of the tractor is the mirror image of the construction on the other side. Accordingly only one side will be described, it being understood that like reference numerals apply to the other side.

The tractor l is shown in outline so that it does not obstruct the view of the construction. A main thrust member 2 which also constitutes a strut of the previously mentioned strut assembly extends alongside the tractor and is pivoted to it at its rear end. At the front it is loosely pivoted to the blade 3. A hollow first link 4 is pivoted to the thrust member 2 and a guide rod 5 slides closely inside the hollow link 4 and is pivoted to the blade 3. Second link 6 is loosely pivoted at one end to first link 4 and at the other end to a bracket 7 which slides along a rail 8 which is fixed to the blade 3.

A lift ram 9 pivoted on the tractor and to the blade operates to lift or lower the blade in known manner. Stabilizer rods 10 prevent the blade from moving sideways.

Two cylinders 11 are fixed in a back-to-back manner to the blade 3. These contain pistons and rods 12 which project, one on each side and are pivotally connected to the brackets 7. A pressure hose 13 is connected to the junction block 14 of the two cylinders and a pressure hose 15 is connected to the outer end of each cylinder 1 1.

Referring now to FIG. 3, the cylinders are now identified as 118 and 11D, and the piston as 128 and 12D. The block 14 has a through passage 16 which connects with hose 13. Each cylinder 11S and 11D are connected to respective hoses 15S and 15D. Thus there are three chambers 17S, 17C, and 17D. Chamber 17C is formed by part of both cylinders 11S and 11D and the passage 16.

When pressure is applied to chamber 17C and chamber 175 and 17D are connected to exhaust pistons 12S and 12D move to the left and right respectively to cause the sub-assembly formed by the first and second links 4 and 6 to extend thus moving the top of the blade 3 forward at both ends in a forward pitching movement. Pressure applied to chamber 175 and 17D while chamber 17C is connected to exhaust causes the pistons 12S and 12D to move toward each other. This movement contracts the two sub-assemblies causing the top of the blade 3 to tip back in an upward pitching movement.

When chamber 17C is closed and pressure is applied to chamber 17D while chamber 175 is connected to exhaust, both pistons move to the left causing the left sub-assembly to extend and the right one to contract. This causes the blade to tilt with the right end of the blade down. The opposite application of pressure causes the blade to tilt the other way.

In the embodiment shown with reference to FIG. I the control for the rams 9 must be in a free floating position in which oil is free to move in or out of these rams without pressure to enable them to accommodate the movement.

FIG. 3 also shows a control valve arrangement which will direct the oil pressure as required above.

A pump 18 feeds oil to a selector valve 19 having six ports and three positions. In the central position all oil is returned to tank 20. In the right hand position of the handle 23 the valve 19 directs oil to and from the pitch control valve 21. In the left hand position the valve directs oil to and from the tilt control valve 22.

Both the pitch and tilt control valves 21 and 22 are spring i loaded to the center position where they isolate all the chambers 17S, 17C, and 17D. All valves 18, 21, and 22 are manually controlled by the driver's hand.

Pitch control valve 21 in the right hand position of its handle 24 directs pressure fluid to chambers 17S and 17D and connects 17C to tank 20. In the left hand position of its handle 24 the control valve 21 directs pressure fluid to chamber 17C and connects both and 17D to tank. Thus the pitching movements referred to above are achieved.

Tilt control valve 22 in the right hand position of its handle 25 directs pressure fluid to chamber 17D, maintain chamber 17C closed, and connects 175 to tank. This causes leftward movement of both pistons 12S and 12D. In the left hand position of the handle 25 the tilt control valve 22 directs the pressure fluid to chamber 17S, maintains chamber 17C closed, and connects 17D to tank. This causes rightward movement of both pistons. Thus the tilting movements referred to above are achieved.

Referring now to FIG. 2, it will be seen that the dozer blade in this case is capable of being angled to one side or the other about a central universal pivot 30. The U-shaped frame 31 is the main thrust member in this case and the sub-assembly includes a separate strut 32 in place of the side member 2. In this embodiment the strut 32 and guide rod are universally pivoted to the blade.

The strut assembly can be pivoted at lug 33 on one side and the lug 34 at the other and corresponding pivot points 35 and 36 are provided on first links 4 to accommodate this change of position.

In FIG. 4, there is shown a symbolic representation of an amplified control system. A pump 40 supplies a three position, six port, spring loaded to center control valve 41. In the center position the oil delivery returns to tank 42. With the upper panel of the valve representation in use the pressure oil is directed to the chamber 17C. The oil pipes 43 and 44 connected to chambers 17S and 17D respectively unite at 45 to become a single pipe 46. An on/off cock (tap) 47 is provided in pipe 44 so that chamber 17D can be isolated.

With tap 47 in the on" position both chambers 17S and 17D are connected to tank when the upper panel of the valve representation is in use. Likewise when the lower panel of the representation is in use pressure oil can flow to chambers 17S and 17D while chamber 17C is connected to tank. Thus the pistons 12S and 12D move oppositely to each other to give pitching movement as before described.

When the tap 47 is closed the chamber 17D is isolated and piston 12D cannot move. In consequence when the upper panel of the valve representation is used pressure oil will flow to chamber 17C, chamber 178 will be connected to exhaust and only piston 128 will move to the left. When the lower panel of the valve representation is used pressure oil will flow to chamber 17S, chamber 17C will be connected to exhaust and only piston 128 will move to the right.

If it is required to tilt the blade so that the right hand end is down it is possible to follow the sequence below:

a. Pitch the blade back by placing tap 47 on" and using the lower panel of the representation so that both pistons are near to each other.

b. Extend the top left corner of the blade forward by closing tap 47 and using the upper panel of the representation so that piston 128 only moves outward.

In general in a tilting movement, the right hand end of the blade is to be down then the top corner of that end must be pitched back before closing the tap 47.

Clearly, at the option of the driver, the sequence can start from a position where the blade is tilted forward and the appropriate controls operated to secure the desired results.

I claim:

1. Bulldozer structure for a tractor comprising a blade extending across the front of the tractor, a pair of strut assemblies each connected at one end to said blade to receive a thrust from said blade and having opposite ends adapted for connection to a tractor for transmitting said thrust to said tractor, each of said assemblies consisting of a strut of fixed length and a sub-assembly of variable length, and power actuating means operable by a tractor, to simultaneously increase or decrease the effective length of the two sub-assemblies to give a pitching movement to the blade, said means also being operable to increase the length of one sub-assembly and decrease the length of the other sub-assembly to give a tilting movement to the blade.

2. Bulldozer structure according to claim 1 characterized in that each sub-assembly consists of a first link pivotally connected at one end of the strut and a second link pivotally connected at one end to the first link and at the other end through a transversely movable ivot t o the blade, and guide means to maintain substantially e positional relationship between the first link and the strut.

3. Bulldozer structure according to claim 2 characterized in that the control means to vary the efi'ective lengths of the subassemblies consists in part of a pair of double acting piston and cylinder rams containing four fluid chambers two of which are permanently connected together to fonn a common chamber, the ram pistons or cylinders being connected to move the movable pivots.

4. Bulldozer structure according to claim 3 characterized in that the piston rods are connected to the movable pivots and a control located near to the driver is provided to direct pressure fluid to the common chamber to cause the pistons to move the movable pivots so that both sub-assemblies are extended or contracted by an equal amount to give a pitching movement.

5. Bulldozer structure according to claim 4 characterized in that the control system includes means to close the common chamber and direct pressure fluid to one of the other chambers to cause both pistons to move their respective movable pivots so that one sub-assembly is extended while the other is contracted or vice versa. 

1. Bulldozer structure for a tractor comprising a blade extending across the front of the tractor, a pair of strut assemblies each connected at one end to said blade to receive a thrust from said blade and having opposite ends adapted for connection to a tractor for transmitting said thrust to said tractor, each of said assemblies consisting of a strut of fixed length and a sub-assembly of variable length, and power actuating means operable by a tractor, to simultaneously increase or decrease the effective length of the two sub-assemblies to give a pitching movement to the blade, said means also being operable to increase the length of one sub-assembly and decrease the length of the other sub-assembly to give a tilting movement to the blade.
 2. Bulldozer structure according to claim 1 characterized in that each sub-assembly consists of a first link pivotally connected at one end of the strut and a second link pivotally connected at one end to the first link and at the other end through a transversely movable pivot to the blade, and guide means to maintain substantially the positional relationship between the first link and the strut.
 3. Bulldozer structure according to claim 2 characterized in that the control means to vary the effective lengths of the sub-assemblies consists in part of a pair of double acting piston and cylinder rams containing four fluid chambers two of which are permanently connected together to form a common chamber, the ram pistons or cylinders being connected to move the movable pivots.
 4. Bulldozer structure according to claim 3 characterized in that the piston rods are connected to the movable pivots and a control located near to the driver is provided to direct pressure fluid to the common chamber to cause the pistons to move the movable pivots so that both sub-assemblies are extended or contracted by an equal amount to give a pitching movement.
 5. Bulldozer structure according to claim 4 characterized in that the control system includes means to close the common chamber and direct pressure fluid to one of the other chambers to cause both pistons to move their respective movable pivots so that one sub-assembly is extended while the other is contracted or vice versa. 